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下面是我的代码。我的应用程序中有一个 meidaplayer。如果用户播放音乐然后离开活动，一切都是正确的，但是当用户离开活动而不播放音乐时，它会导致强制关闭。

有什么问题？

public class Elementary1Activity extends Activity implements Runnable, OnClickListener, OnSeekBarChangeListener{
        private SeekBar seekBar;
        private ImageButton startMedia;
        private ImageButton pauseMedia;
        private MediaPlayer mp;

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.elementary1);             

            TextView title1 = (TextView) findViewById(R.id.title1);
            TextView tx1 = (TextView) findViewById(R.id.textView1);
            Typeface font = Typeface.createFromAsset(getAssets(), "font.ttf");
            title1.setTypeface(font);
            tx1.setTypeface(font);

            AudioControl();    



        }



        public void AudioControl(){
            seekBar = (SeekBar) findViewById(R.id.seekBarnew2);
            startMedia = (ImageButton) findViewById(R.id.playbuttonnew2);
            pauseMedia = (ImageButton) findViewById(R.id.pausebuttonnew2);
            seekBar.setOnSeekBarChangeListener(this);
            startMedia.setOnClickListener(this);
            pauseMedia.setOnClickListener(this); 
        }



        public void run() {
            int currentPosition= 0;
            int total = mp.getDuration();
            while (mp!=null && currentPosition<total) {
                try {
                    Thread.sleep(1000);
                    currentPosition= mp.getCurrentPosition();
                } catch (InterruptedException e) {
                    return;
                } catch (Exception e) {
                    return;
                }            
                seekBar.setProgress(currentPosition);
            }
        }

        public void onClick(View v) {
            pauseMedia.setVisibility(View.VISIBLE);
            seekBar.setVisibility(View.VISIBLE);
            startMedia.setVisibility(View.INVISIBLE);
            if (v.equals(startMedia)) {
                if (mp != null && mp.isPlaying()) return;
                if(seekBar.getProgress() > 0) {
                    mp.start();
                    return;
                }
                mp = MediaPlayer.create(Elementary1Activity.this, R.raw.e1);
                mp.start();            

                seekBar.setProgress(0);
                seekBar.setMax(mp.getDuration());
                new Thread(this).start();
            }

            if (v.equals(pauseMedia) && mp!=null) {
                mp.pause();
                pauseMedia.setVisibility(View.INVISIBLE);
                startMedia.setVisibility(View.VISIBLE);

            }       

        }



        public void onStartTrackingTouch(SeekBar seekBar) {
        }

        public void onStopTrackingTouch(SeekBar seekBar) {
        }

        public void onProgressChanged(SeekBar seekBar, int progress,
                boolean fromUser) {
            if(fromUser) mp.seekTo(progress);

        }

        public void onStop() {
               super.onStop();
               mp.stop();
            }
    }
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1 回答 1

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据我所知，如果用户离开您的活动，这意味着用户使用后退按钮或执行其他使应用停止的操作，对吗？如果是，我认为问题在于您此时没有初始化您的 MediaPlayer。您首先在按钮单击时初始化此 MediaPlayer，但在 onStop() 中您正在停止未初始化的 MediaPlayer。在 onCreate() 中初始化您的 MediaPlayer：

      @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.elementary1);             

        TextView title1 = (TextView) findViewById(R.id.title1);
        TextView tx1 = (TextView) findViewById(R.id.textView1);
        Typeface font = Typeface.createFromAsset(getAssets(), "font.ttf");
        title1.setTypeface(font);
        tx1.setTypeface(font);
        mp = MediaPlayer.create(Elementary1Activity.this, R.raw.e1);


        AudioControl();    



    }

我还没有测试你的代码，但如果这不起作用，还有另一个错误，我没有搜索过。但这绝对是错误的。

于 2013-07-14T22:09:10.077 回答